A high frequency heating apparatus having a high frequency wave generating means for outputting a high frequency wave into a heating chamber in which a heating target to be heated is accommodated can efficiently heat the heating target in the heating chamber in a short time, and thus it has become rapidly widespread as a microwave oven which is a cooling instrument for foodstuff.
However, only the heating based on the high frequency heating limits the range of cooling or the like, and thus it has been inconvenient.
Therefore, there has been proposed a high frequency heating apparatus with which oven heating can be performed by adding an electric heater heating in the heating chamber, and further there has been also recently proposed a high frequency heating apparatus having a steam generating function with which cooking with high-temperature steam can be also performed by further adding a steam supply mechanism for supplying heating steam to the heating chamber (for example, see patent document 1).
(Patent Document 1) JP-A-54-115448
The steam supply mechanism of the conventional high frequency heating apparatus is designed to be equipped with a water tank detachably secured to the main body of the apparatus, a water supply tray mounted in the heating chamber, heating means for heating the water supply tray and vaporizing water on the water supply tray, and dedicated pump means for supplying water in the water tank to the water supply tray, and the equipment of the pump means causes a problem that the construction of the apparatus is complicated and large in size.
Furthermore, in the conventional steam supply mechanism using the dedicated pump means, in order to control the supply amount of steam to the heating chamber, it is required to control the supply amount based on the pump means simultaneously with temperature control of the heating means, and thus there is a problem that the control treatment needed for the supply amount control of steam is complicated.
Furthermore, water stocked in the water tank is fed to the water supply tray by the dedicated pump means, and during this feeding operation, the water is fed without being subjected to preliminary heating or the like (in order to avoid occurrence of a pump trouble due to hot water). Therefore, there is also a problem that the temperature of the water supplied to the water supply tray is low and it takes a long time to heat the water supply tray and generate steam by the heating means.
The present invention has been implemented in view of the foregoing problem, and has an object to provide a high frequency heating apparatus having a steam generating function with which there is required no dedicated pump means for supplying water in a water tank to a water supply tray, simplification and miniaturization of the construction of a steam supply mechanism can be implemented by omitting the pump means, control processing needed to control the supply amount of steam can be simplified, and steam-heating can be rapidly performed by shortening a time required to generate steam.